CN87103486A - Gold doping, mix platinum single crystal silicon interchangeable thermistor and preparation method thereof - Google Patents

Abstract

The invention provides a kind of gold doping, mix platinum single crystal silicon interchangeable thermistor and preparation method thereof, belong to the temperature sensor technical field.It mainly adopts the method for mixing gold, two kinds of impurity of platinum in p type single crystal silicon, makes resistance present negative temperature characteristic, and its B value is 3850K, and the deviation profile of B value is less than ± 0.3%, and using warm area is between-50 ℃～100 ℃.Because the B value of this resistive element is moderate, the exchange performance is good, easily makes again, and is with low cost, a kind of ideal element that is used to prepare the linear modules with linear output of can yet be regarded as.And can be widely used in the practical technique field such as thermometric, temperature control of industries such as Medical Instruments, food industry, household electrical appliance.

Description

The invention belongs to the technical field of temperature sensor.

Be used in the monocrystalline thermistor that the method for mixing deep-level impurity in the monocrystalline silicon makes, the consistency of its resistance-temperature characteristics is greatly improved than oxidate semi-condcutor thermo-sensitive resistance, can satisfy the interchangeability requirement in using preferably, obtains increasingly extensive application.

Tokyo Zhi Pu Electric Co., Ltd once proposed a kind of manufacture method (the clear 58-32481 of Japan's special permission) of silicon single crystal thermal sensitive resistor.They adopt the method for mixing golden impurity in P type or N type silicon single crystal, made the thermistor with negative temperature coefficient, its B value is 4900K, and the deviation profile of the resistance in the time of 30 ℃ is less than ± 0.5%, but minimum serviceability temperature only reaches-20 ℃, and is not to exchange.About the exchange performance being played the discrete case of the B value of main influence, in this patent documentation is open, do not provide the result.The product advertising introduction of the silicon thermistor that provides according to Tokyo electronics Institute of Metallurgical Technology, it is-30 ℃～100 ℃ that this product uses warm area, the deviation profile of B value is ± 2～3%, the deviation profile of resistance is ± 2% in the time of 25 ℃, and this reflects the main performance index of present silicon single crystal thermal sensitive resistor.

The interchangeability of the thermistor that proposes for the satisfied temperature measuring instrument requires and is produced on the needs of the linear modules that has linear output in the broad warm area, wish to obtain the B value at 4000K or lower silicon single crystal thermal sensitive resistor, simultaneously, the deviation profile of its B value requires littler than existing product.And purpose of the present invention, just provide a kind of in p type single crystal silicon gold doping, the method for mixing platinum, thereby obtain the B value and be 3850K, the use warm area is-50 ℃～100 ℃ a single crystal silicon interchangeable thermistor, the deviation profile of its B value is less than ± 0.3%, the deviation profile of resistance is less than ± 0.3%, to satisfy the interchangeability requirement of degree of precision in the time of 25 ℃.

Thermistor provided by the present invention is to mix gold and two kinds of impurity of platinum in P type silicon single crystal simultaneously, makes in the forbidden band to occur apart from the platinum donor level of top of valence band 0.30ev, the golden donor level of 0.35ev and the platinum acceptor level of 0.36ev.When original shallow acceptor concentration in the concentration ratio monocrystalline of these energy levels was a lot of greatly, because the compensating action of these energy levels, material presented negative temperature characteristic, and its B value is about 3850K.The method of mixing gold and platinum in P type silicon single crystal simultaneously mainly adopts the method for diffusion, promptly selects for use the P type silicon single crystal of high resistant rate to make substrate, at first spreads platinum down at 1200 ℃, makes the concentration of platinum reach 1 * 10 ¹⁴Cm ³More than, in 800 ℃～1200 ℃, spread gold then under a certain temperature, make monocrystalline silicon reach satisfactory resistivity.The temperature of diffusion gold is high more, and the resistivity that obtains is high more.Under different gold doping temperature, its B value can be adjusted between 3800K～3900K; Through the silicon single crystal of twice diffusion, and be cut into the thermistor that the chip of 1mm * 1mm is made, its room temperature resistance value can be adjusted between hundreds of ohm to tens kilohm.

Accompanying drawing 1 for gold doping, mix the contour structures schematic diagram of platinum single crystal silicon interchangeable thermistor.Wherein, the method for the available chemical nickel plating of double-sided electrode (2) of chip (1) is made.Lead-in wire (4) is the silver-coated copper wire of 0.2mm, is welded on the electrode (2) with scolding tin (3).Entire chip seals with epoxy resin (5).Utilize the resistance-temperature characteristic of the thermistor that above-described method makes can be referring to accompanying drawing 2.Ordinate among the figure (logarithmic coordinates) is the resistance R of thermistor, and unit is ohm (Ω).The abscissa of Fig. 2 below be absolute temperature inverse (1000 * 1/T), marked corresponding celsius temperature scale on the abscissa of Fig. 2 top.As shown in Figure 2, in-50 ℃～100 ℃ warm area scopes, it satisfies R=R fully ₀EXP(B/T) exponential relationship, the B value is about 3850K; The deviation profile of element B value is less than ± 0.3% in batches; The deviation profile of 25 ℃ of resistances is less than ± 0.3%; In-50 ℃～100 ℃ warm areas different resistive elements be not more than in the deviation profile of the resistance of same temperature spot ± 2%, can reach the requirement of exchanging in batches, simultaneously, resistive element was through 1000 hours, behind 100 ℃ of high temperature ageings, its resistance deviation is less than ± 0.5%, time constant is 1.5～5(second) dissipation factor reach 1.5～2.5(milliwatt/℃), and this resistance is easy to manufacture, with low cost, be widely used in Medical Instruments, food industry, the thermometric of industries such as household electrical appliance, practical technique fields such as temperature control, because the B value of this resistive element is moderate, interchangeability is good, so it is the ideal element that preparation has the linear modules of linear output.

Embodiment.Adopting resistivity is the P type silicon single crystal of 148 ohmcms, is cut into the wafer of 0.3 millimeters thick, after polishing, cleaning, is coated with source platinum expansion 6 hours under 1200 ℃; The platinum source restrains in 5 with specpure chloroplatinic acid and top grade absolute alcohol: 95 milliliters ratio is made into.The oxide layer that wafer after the diffusion is removed silicon chip surface with hydrofluoric acid, gold was expanded 2 hours in the source that is coated with under 1200 ℃ again; Jin Yuan restrains in 5 with specpure chlorauride and the pure alcohol of top grade: 95 milliliters ratio is formulated.Wafer after the secondary diffusion carries out chemical nickel plating through after removing oxide layer; The prescription of nickel-plating liquid is nickel chloride 30 grams, inferior sodium phosphate 10 grams, ammonium chloride 50 grams, ammonium citrate 65 grams, deionized water 1000 grams.At last wafer is divided into 1 millimeter * 1 millimeter chip, the silver-coated copper wire of 0.2 millimeter of φ in the soldering of the two sides of chip; Wore out 800 hours down at 100 ℃, resistance is the element of 5.60K Ω when obtaining 25 ℃ behind mechanical resistance trimming.During encapsulation, be coated with one deck PPS glue (component 148%, component 252%) earlier, use epoxy sealing again.Epoxy resin is in ESI: polyethylene polyamine=10 grams: the ratio preparation of 0.9 gram, and add 1% alumina powder and an amount of colorant and do filler.The element that makes so all can reach the index that proposes previously through every index test.

Claims (2)

1, a kind of single crystal silicon interchangeable thermistor and preparation method thereof, be primarily characterized in that it is that a kind of employing p type single crystal silicon is made substrate, mix platinum and two kinds of impurity of gold through High temperature diffusion, make the resistivity of monocrystalline silicon present negative temperature characterisitic, its B value is 3850K, the deviation profile of B value less than ± 0.3% gold doping, mix platinum single crystal silicon interchangeable thermistor.

2, gold doping according to claim 1, mix platinum single crystal silicon interchangeable thermistor, its B value can be between 3800K～3900K between 800 ℃～1200 ℃ the time for the gold doping temperature that it is characterized in that it, resistance can be between hundreds of ohm to tens kilohm in the time of 25 ℃, behind mechanical resistance trimming, its resistance 25 ℃ of resistance deviation profile less than ± 0.3%.

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